This invention relates to the metering of particles, and more particularly to the controlled metering or dispensing of particles from a supply thereof. The invention finds particular application to the dispensing of individual seeds for planting purposes.
Particle metering, and in particular seed metering, has typically been accomplished in the past through mechanical means involving contact of the particles being metered by moving machine parts. Such contact is undesirable, especially in the field of seed metering. The present invention, accordingly, is directed to the metering of particles through the use of fluid flows, eliminating entirely the need for mechanically moving parts in contact with the particles.
The invention utilizes the circulation of particles through a circulation passage by fluid flow through the passage. A counterflow of fluid within the passage is utilized in part to retain a single particle within a particle retention chamber that forms a part of the passage. The retained particle is then ejected from the particle retention chamber through the use of fluid flow passing through an ejection passage that communicates with the particle retention chamber. By appropriate correlation of fluids applied to different zones of the circulation and ejection passages, the circulation and retention and ejection of particles may be easily achieved.
The ejection or dispensing of particles on a periodic basis may be achieved through periodic activation of one or more sources of fluid under pressure that provide for the fluid flows within the passages. Such periodic activation may, for example, be associated with the movement of a seed planter so that seeds are dispensed for planting based upon such movement. The dispensing of particles through the ejection passage may be monitored, so that if a seed, for example, is not dispensed on the periodic basis for some reason, then an additional ejection operation can be carried out to ensure the appropriate planting of seeds. Monitoring of the movement of a particle through the ejection passage may be achieved by detecting the pressure at one or more points in the ejection passage and noting pressure changes as produced by particles passing through the passage.
The following patents are representative of the prior art:
______________________________________ U.S. Patent No. Patentee(s) Issued ______________________________________ 3,142,274 Winter 28 July 1964 3,201,062 Mach et al. 17 Aug. 1965 3,466,079 Mammel 9 Sept. 1969 3,504,945 Leibundgut et al. 7 Apr. 1970 3,556,604 Round 19 Jan. 1971 ______________________________________